This appendix contains information regarding the modules that
can be found in the contrib directory of
the PostgreSQL distribution.
These include porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental
to be part of the main source tree. This does not preclude their
usefulness.

When building from the source distribution, these modules are
not built automatically, unless you build the "world" target (see
step 2). You can build
and install all of them by running:

gmakegmake install

in the contrib directory of a
configured source tree; or to build and install just one selected
module, do the same in that module's subdirectory. Many of the
modules have regression tests, which can be executed by
running:

gmake installcheck

once you have a PostgreSQL
server running. (Note that gmake check
is not supported; you must have an operational database server to
perform these tests, and you must have built and installed the
module(s) to be tested.)

If you are using a pre-packaged version of PostgreSQL, these modules are typically made
available as a separate subpackage, such as postgresql-contrib.

Many modules supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have
installed the code you need to register the new SQL objects in
the database system. In PostgreSQL 9.1 and later, this is done by
executing a CREATE
EXTENSION command. In a fresh database, you can simply do

CREATE EXTENSION module_name;

This command must be run by a database superuser. This
registers the new SQL objects in the current database only, so
you need to run this command in each database that you want the
module's facilities to be available in. Alternatively, run it in
database template1 so that the extension
will be copied into subsequently-created databases by
default.

Many modules allow you to install their objects in a schema of
your choice. To do that, add SCHEMA
schema_name to the
CREATE EXTENSION command. By default,
the objects will be placed in your current creation target
schema, typically public.

If your database was brought forward by dump and reload from a
pre-9.1 version of PostgreSQL,
and you had been using the pre-9.1 version of the module in it,
you should instead do

CREATE EXTENSION module_name FROM unpackaged;

This will update the pre-9.1 objects of the module into a
proper extension object. Future updates
to the module will be managed by ALTER EXTENSION. For more
information about extension updates, see Section 35.15.

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